A prior art device for exercising waist and legs comprises a pivoting tube for each of two pedals. Located under the pivoting tube is an urging block under which a first connection rod is horizontally disposed. The first connection rod is fastened pivotally with a second connection rod which is in turn fastened pivotally with a main support rod. When the two pedals move up and down in rotation, the main support rod remains stationary. As the pedals are moved downward, the urging blocks push the first connection rod and the second connection rod to swivel. This prior art device is defective in design in that the urging blocks, the first connection rod, and the second connection rod are vulnerable to jam, thereby resulting in high rate of mechanical breakdown.
Another prior art device for exercising waist and legs comprises a pedalling apparatus which is connected at the front end thereof with a straight rod which is in turn fastened horizontally with a connection rod mechanism. An upright rod is fastened with the connection rod mechanism such that the upright rod is connected with the radial periphery of a rotary disk. When two pedals are moved up and down, the connection rod mechanism is pushed by the straight rod such that the rotary disk is actuated to turn by the upright rod. This prior art device is composed of many component parts, such as the straight rod, the connection rod mechanism, an upright rod, a rotary disk, etc. These component parts are prone to move apart to result in the jamming of the prior art device.